Updated to phpunit/phpunit v5.5.6

Author: Torann

composer.json

@@ -18,7 +18,7 @@
     "illuminate/support": "~5.1"
   },
   "require-dev": {
-    "phpunit/phpunit": "^4.8",
+    "phpunit/phpunit": "~5.0",
     "mockery/mockery": "^0.9.4"
   },
   "autoload": {